tpm: Don't make log failures fatal

commit 805fa88e upstream.

If a TPM is in disabled state, it's reasonable for it to have an empty
log. Bailing out of probe in this case means that the PPI interface
isn't available, so there's no way to then enable the TPM from the OS.
In general it seems reasonable to ignore log errors - they shouldn't
interfere with any other TPM functionality.
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
Cc: stable@vger.kernel.org # 4.19.x
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/tpm/eventlog/common.c

@@ -104,11 +104,8 @@ static int tpm_read_log(struct tpm_chip *chip)
  *
  * If an event log is found then the securityfs files are setup to
  * export it to userspace, otherwise nothing is done.
- *
- * Returns -ENODEV if the firmware has no event log or securityfs is not
- * supported.
  */
-int tpm_bios_log_setup(struct tpm_chip *chip)
+void tpm_bios_log_setup(struct tpm_chip *chip)
 {
 	const char *name = dev_name(&chip->dev);
 	unsigned int cnt;
@@ -117,7 +114,7 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 
 	rc = tpm_read_log(chip);
 	if (rc < 0)
-		return rc;
+		return;
 	log_version = rc;
 
 	cnt = 0;
@@ -163,13 +160,12 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 		cnt++;
 	}
 
-	return 0;
+	return;
 
 err:
-	rc = PTR_ERR(chip->bios_dir[cnt]);
 	chip->bios_dir[cnt] = NULL;
 	tpm_bios_log_teardown(chip);
-	return rc;
+	return;
 }
 
 void tpm_bios_log_teardown(struct tpm_chip *chip)

drivers/char/tpm/tpm-chip.c

@@ -463,9 +463,7 @@ int tpm_chip_register(struct tpm_chip *chip)
 
 	tpm_sysfs_add_device(chip);
 
-	rc = tpm_bios_log_setup(chip);
-	if (rc != 0 && rc != -ENODEV)
-		return rc;
+	tpm_bios_log_setup(chip);
 
 	tpm_add_ppi(chip);
 

drivers/char/tpm/tpm.h

@@ -602,6 +602,6 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u32 cc,
 int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
 		      u32 cc, u8 *buf, size_t *bufsiz);
 
-int tpm_bios_log_setup(struct tpm_chip *chip);
+void tpm_bios_log_setup(struct tpm_chip *chip);
 void tpm_bios_log_teardown(struct tpm_chip *chip);
 #endif